This project aims to: (1) determine the relationship between performance on a standardized max treadmill test and performance on the 400m component of the LDCW, including variation by fitness level; (2) obtain an estimate of VO2max from time to complete 400m, among other parameters (e.g., ending HR, weight, sex, age); (3) determine the need to increase test ceiling; (4) obtain additional data on the relationship between 20m walking speed, 2-min distance, and 400m time; and (5) evaluate the advantages of the LDCW over treadmill-based tests for measuring exercise tolerance in older adults. Subjects consist men and women, 60 years or older participating in the BLSA who performed a maximal treadmill-walk test. Subjects were administered the Health ABC LDCW as part of their regular visit for the BLSA, the day after treadmill testing. The primary outcomes are to provide: (1) a validated alternative to max treadmill-based tests of exercise tolerance that is safe and acceptable for use in longitudinal population-based studies of older adults and (2) equations for estimating VO2max from time to walk 400m applicable to older adults. We anticipate that validation of a low cost and safe alternative to treadmill testing will promote more widespread inclusion of exercise tolerance testing in studies of older adults and thereby facilitate increased understanding of the disabling process. In addition, the LDCW has the potential for use in clinical settings as an indicator of preclinical functional decline and for screening to identify those most in need of early intervention. The protocol received IRB approval in April 1999 and testing was initiated in August 1999. Data collection was completed in July 2000 with 107 subjects with valid treadmill results enrolled. A poster was prepared using data on 67 subjects and presented to the Board of Scientific Counselors in May 2000.